1. Field of the Invention
The present invention relates to a method of operating an apparatus for producing conveyer belts of rubber or rubber-like synthetic material, i.e. elastomeric material, in which are embedded wire or cord-like load-carriers that extend parallel to one another in the longitudinal direction without contacting one another. Means are provided for jointly keeping the load-carriers under tension within a lengthy portion of the apparatus. Also provided are a plurality of tensioning cylinders that are disposed in the vicinity of the input region of the aforementioned portion of the apparatus. Each tensioning cylinder has a piston that can be displaced by pressure medium, with each piston having a piston rod. Provided on each piston rod is a tensioning roller that engages a respective one of the load-carriers.
2. Description of the Prior Art
An apparatus of this general type is known, for example, from German patent No. 1 579 102 Michels et al dated July 13, 1972 and belonging to the assignee of the present invention. After the significance of maintaining a constant tension over the entire length of the apparatus in the load-carriers, not only when progress is halted, but also during the course of the feed movements became known, such apparatus were exclusively preferred over other, continuously operating apparatus, for producing high-quality conveyer belts that contain steel wires. In all cases, the tensioning cylinders that additionally act upon the individual load-carriers constitute an important component, because taken as a whole these cylinders always adjust the different lengths of the load-carriers relative to one another, and hence create the conditions for achieving a uniform tension in all of the load-carriers. Pursuant to generally existing views, and already due to logical considerations, the desired uniform distribution of tension should immediately and automatically result over the width of the load-carrying-containing band that is passed through the apparatus when all of the tensioning cylinders are acted upon by pressure medium from a single source. However, practical experience with the heretofore known apparatus seems to disprove such a theory. In particular, irregularities in the quality of the finished conveyer belts surprisingly occurred continuously. The cause of such irregularities was clearly differences in tension in the embedded load-carriers.
An object of the present invention therefore is to maintain the desired uniform distribution of tension in the load-carriers independent of disruptive external influences, and to thereby indirectly ensure the utility and durability of the conveyer belt that is produced.